近50年来华北平原极端干旱事件的时空变化特征

Temporal-spatial Variation Characteristics of Extreme Drought Events in North China Plain During Recent 50 Years

根据华北平原35个气象站点1962—2011年的气象资料,利用线性倾向估计法、反距离加权插值法、Mann—Kendall突变检验等方法对华北平原年际、年代际极端干旱变化特征及影响其变化的气候因子进行了分析。研究结果表明,华北平原近50a来极端干旱发生频率以0.013 5次/a的速率下降,春、夏季与年极端干旱发生频率的变化趋势相一致,而秋、冬季则与其相反;研究区内,年极端干旱发生频率呈增加趋势的区域零星分布。1962—1969年和20世纪80年代,华北平原极端干旱发生频率为正距平,其他年代均为负距平;空间分布上,1962—1989年极端干旱的高发区逐年代扩大,20世纪90年代以来,极端干旱的高发区明显缩小,低发区显著扩大,2000年以后,低发区几乎覆盖了整个华北平原。近50a来,华北平原的年极端干旱频率在2003年发生突变,春、夏、秋、冬各季分别在1993,1998,1987和2002年发生突变;极端干旱发生频率与日照时数、平均风速、潜在蒸散量、平均气温呈正相关性,与降水量、相对湿度之间存在明显的负相关关系。

According to the meteorological data of 35 stations in North China Plain from 1962 to 2011, this study analyzed the variation characteristics of the extreme drought frequency in inter-annual, inter-decadal and its impact factors by using linear tendency estimate, inverse distance weighted interpolation, M--K mu- tations test and so on. The results are indicated as follows： The extreme drought frequency in North China Plain decreased in the past 50 years with a rate of 0. 013 5 times per year. The changes of extreme drought frequency in spring and summer were consistent with that of all year around, but contrary changes were showed in autumn and winter. The areas where the year-round extreme drought frequency presented increas- ing trend were distributed scatteredly in the researched area. The extreme drought frequency in North China Plain showed a positive departure in 1962--1969 and 1980s, but it was negative departure in other decades. At spatial scale, the areas where extreme drought occurred frequently expanded decade by decade from 1962 to 1989, but they shrunk obviously since 1990s. The areas where extreme drought frequency was compara- tively low expanded significantly since 1990s and which covered nearly all the North China Plain since 2000. In recent 50 years, the year-round extreme drought frequency in North China Plain changed abruptly in 2003 and the abrupt change in spring, summer, autumn, winter occurred in 1993, 1998, 1987, 2002, respectively. The extreme drought frequency showed a positive correlation with sunshine duration, average wind speed, potential evaporation, average temperature, while it showed a negative correlation with precipitation and relative humidity.